Thanks for the explanation. So does that mean with a 10K (instead of a 100K), it'd charge it faster and be less likely to hear any pop?

In terms of that same resistor, does it load down the outgoing signal at all in any adverse way (100k vs 10k)?

Almost ”no”. Make sure that it doesn't lower the corner frequency of the high pass filter created by Cout and R pull-down in parallel with Rin of the next stage by an unacceptable amount.
Make sure that the op-amp has sufficient output current to drive both R pull-down and R in in parallel.
The drop in voltage due only to the decreases resistance will be small, because of the low output resistance of an op-amp with feedback.
Your 9V battery has to supply the current through the pull-down resistor, and that may reduce the battery life.

 

Curious, are any additional pedals connected in series or parallel?

 

Curious, are any additional pedals connected in series or parallel?

In my latest testing, yes. This tuner pedal is the first in the chain of 4 others in series.

 

Awesome! Just switched that RPDO to 10K and with 10u + 10K there's zero popping noise after initial power up of the pedal. Thanks all!

 

There are different styles, routines for setting for a song. I'm showing this video because knowing how the guitarist uses the controls
is significant to the design and not just what the "dude" will pay for, but what they are looking for in its operation, not so much exact.
The Plon Fentaur buffer was expanded to the Clon Centaur starting in 1990. Bill Finnegan's team used triangle waves, they completed in 1994.
One of the design goals was to push the head amp to the breaking point. I think the gain control belongs to the Plon. Possibly a 100k pot
having digital control, too much of that stuff means faster microcontroller. In the video below shows guitarist making adjustments in particular the gain.

There are routines that a guitarist uses with the controls in getting a match between his reference tone for getting ready to play the next song.
Going back to retro, He says "Sometimes I mess the whole thing up." An arduino guitar controller reminds me of karaoke system,
The variety of tunes is large and listening to short wave file to help recall what the tune sounds like. No doubt, future add-ons circuits will be needed.
Playing and routing an instant wave in a user-friendly loop could be improved in digital oscilloscopes and FFT to sample and better analyze audio.
Technically a unity buffer should not add anything to the output like color, it gives a circuit the ability to impedance match.